[Haskell-beginners] How to understand the type "ShowS"?

Prelude> :i ShowS type ShowS = String -> String -- Defined in `GHC.Show' It is a type of a function? I cannot understand this type, and don't know how to create functions of this type. And this function "shows" Prelude> :i shows shows :: Show a => a -> ShowS -- Defined in `GHC.Show' I don't know how this function works. Yi